Disclosed are intermediate transfer members, and more specifically, intermediate transfer members useful in transferring a developed image in an electrostatographic, for example xerographic, including digital, image on image, and the like, printers, machines or apparatuses. In embodiments, there are selected intermediate transfer members comprised of a single layer, or multi layers, such as a dual layer intermediate transfer member comprised of, for example, a polyimide bottom or support layer, and a POSS modified polyimide surface layer, and wherein each layer of the member further comprises a conductive component. The POSS modified polyimide can, for example, be generated in situ by mixing a functional POSS, such as POSS amines, POSS alcohols, POSS carboxylic acids, or POSS epoxides, with a polyamic acid solution (polyimide precursor) followed by the subsequent coating on a support layer followed by curing. In embodiments, the POSS amines, POSS alcohols, POSS carboxylic acids, or POSS epoxides react with the carboxylic acid or amine group of the polyamic acid (polyimide precursor) during the imidization, thus chemically bonding or chemically attached to the resulting polyimide.
The single layered member is comprised of a POSS modified polyimide generated, for example, by the in situ mixing of a functional POSS, such as POSS amines, POSS alcohols, POSS carboxylic acids, or POSS epoxides with a polyamic acid solution (polyimide precursor) followed by subsequent coating of the product resulting from the mixture on a metal substrate and curing, and then releasing the coating from the substrate.
POSS refers, for example, to a polyhedral silsesquioxane, and more specifically, to a oligomeric polyhedral silsesquioxane or a polyhedral oligomeric silsesquioxane (POSS), like POSS RSiO1.5, where R is an alkyl with, for example, from about 1 to about 18 carbon atoms, or from about 4 to about 8 carbon atoms; aryl with, for example, from about 6 to about 42 carbon atoms, or from about 6 to about 24 carbon atoms.
The intermediate transfer members of the present disclosure, in embodiments thereof, possess a number of advantages, such as an acceptable functional resistivity, excellent layer/layer adhesion for the multilayered members, a hydrophobic surface layer, excellent surface tension characteristics (high contact angle), hydrophobic characteristics, excellent dimensional stability, excellent image transfer properties, and acceptable mechanical properties such as scratch resistance.
In a typical electrostatographic reproducing apparatus, a light image of an original to be copied is recorded in the form of an electrostatic latent image upon a photosensitive member, and the latent image is subsequently rendered visible by the application of electroscopic thermoplastic resin particles and colorant, which are commonly referred to as toner. Generally, the electrostatic latent image is developed by bringing a developer mixture into contact therewith. The developer mixture can comprise a dry developer mixture, which usually comprises carrier granules having toner particles adhering triboelectrically thereto, or a liquid developer material, which may include a liquid carrier having toner particles dispersed therein. The developer material is advanced into contact with the electrostatic latent image, and the toner particles are deposited thereon in image configuration. Subsequently, the developed image is transferred to a copy sheet. It is advantageous to transfer the developed image to a coated intermediate transfer web, belt or component, and subsequently transfer with a high transfer efficiency the developed image from the intermediate transfer member to a permanent substrate. The toner image is subsequently usually fixed or fused upon a support, which may be the photosensitive member itself, or other support sheet such as plain paper.
In electrostatographic printing machines wherein the toner image is electrostatically transferred by a potential difference between the imaging member and the intermediate transfer member, the transfer of the toner particles to the intermediate transfer member, and the retention thereof should be substantially complete so that the image ultimately transferred to the image receiving substrate will have a high resolution. Substantially 100 percent toner transfer occurs when most or all of the toner particles comprising the image are transferred, and little residual toner remains on the surface from which the image was transferred.
A disadvantage of using an intermediate transfer member is that a plurality of transfer steps is usually needed allowing for the possibility of charge exchange occurring between toner particles and the transfer member which ultimately can lead to less than complete toner transfer. This results in low resolution images on the image receiving substrate and also image deterioration. When the image is in color, the image can additionally suffer from color shifting and color deterioration with a number of transfer stops.
In embodiments, the resistivity of the intermediate transfer member is within a range to allow for sufficient transfer. It is also desired that the intermediate transfer member have a controlled resistivity, wherein the resistivity is virtually unaffected by changes in humidity, temperature, bias field, and operating time. In addition, a controlled resistivity is of value so that a bias field can be established for electrostatic transfer. Also, it is of value that the intermediate transfer member not be too conductive as air breakdown can possibly occur.
In U.S. Pat. No. 6,397,034 there is disclosed the use of a fluorinated carbon filler in a polyimide intermediate transfer member layer. However, there are disadvantages associated with these members, such as undissolved particles that frequently bloom or migrate to the surface of the polymer layer which leads to nonuniform resistivity characteristics, which in turn causes poor antistatic properties and poor mechanical strength. Also, the ionic additives present on the surface of the transfer member, such as in the form of a belt may interfere with toner release, and bubbles may appear in the conductive polymer layer, some of which can only be seen with the aid of a microscope, others of which are large enough to be observed with the naked eye, resulting in poor or nonuniform electrical properties and poor mechanical properties.
In addition, the ionic additives themselves are sensitive to changes in temperature, humidity, and operating time. These sensitivities often limit the resistivity range of the transfer member. For example, the resistivity usually decreases by up to two orders of magnitude or more as the humidity increases from about 20 to 80 percent relative humidity. This effect limits the operational or process latitude of the intermediate transfer member.
Therefore, it is desired to provide intermediate transfer members with a number of the advantages illustrated herein and weldable intermediate transfer belts, which have excellent transfer ability. It is also desired to provide a weldable intermediate transfer belt that may not have puzzle cut seams, but instead has a weldable seam, thereby providing a belt that can be manufactured without such labor intensive steps as manually piecing together the puzzle cut seam with one's fingers, and without the lengthy high temperature and high humidity conditioning steps. In addition, it is also desired to provide an acceptable circumference weldable belt for color xerographic machines, inclusive of solid ink printers.